This special issue asks ‘What is violence?’ and as such it makes good on sociology’s neglect of what, by any account, constitutes a pressing reality for millions. Indeed, while the ‘scale and pervasiveness of violence today call urgently for serious analysis’ (Bernstein, Leys and Panitch, 2008: 6), sociologists and social theorists have been slow to respond. The contributors to this special issue are helping sociology to catch up, reflecting, as they do, on what is also an incredibly complex reality. Indeed, because violence is complex, the contributors do not offer any easy answers as to how we might understand it; nor do they provide a unified response, since doing so would be at odds with the aim of this special issue, which minimally is to render violence more complex, not less: violence will remain a ‘slippery concept’ (Scheper-Hughes and Bourgois, 2004: 1). That said, violence is not just one concept among many, but a meta-concept (Bishop and Phillips, 2006); and as such it demands meta-analysis, which includes not only a questioning of the ontology of violence, as Sylvia Walby argues (2009; 2012), but a concomitant questioning of what we, as sociologists, can know of violence and how. Theorizing violence, that is, requires an interrogation also of what it is we mean by ‘understanding’ violence, and what makes understanding a ‘possibility’. But for the moment the question remains: why does sociology lack a tradition of studying and theorizing violence? Why is there no ‘sociology of violence’, when, as Walby makes clear, ‘the deployment and regulation of violence are social processes’ (2009: 216): with violence itself ‘socially patterned, embedded in institutions and regimes of inequalities’ (2009: 217)? Why, then, as Walby also writes, has the ‘importance of violence for people’s well-being’ been ‘much underestimated’ and ‘frequently rendered invisible’ within the canon of social